Ablett's importance in the history of Trade Unionism in South Wales is twofold: he was one of the leaders of the opposition to the older miners’ leaders like William Abraham (Mabon, q.v.), and he became a propagandist for Syndicalist and Marxist ideas among the miners. Others had opposed Mabon before Ablett, and as a result had organised one union, the South Wales Miners' Federation, to take the place of the many small local unions; they had also ended the Sliding Scale agreement negotiated by Mabon which had controlled miners’ wages from 1875 to 1903. Their opposition was based on principles of trade union organisation and interests. Ablett on the other hand based his opposition on his view that there was an irreconcilable conflict between the owners and workers in a capitalist society. He opposed any move to conciliate or compromise with the owners and called for the use of the strike not merely for improvement in the lot of the worker but to eliminate the owners altogether. To this end he advocated general strikes to foment a spirit of class warfare.

He first became prominent in the violent and bitter dispute in the Rhondda when there was a strike in the pits owned by the Cambrian Combine, to establish a guaranteed minimum wage. The strike lasted from Oct. 1910 to Sept. 1911. Rioting broke out and additional police forces and detachments of troops were sent into the valley. Ablett issued a manifesto to the miners in favour of a general strike, and opposed accepting the terms of the owners. But after the hardships of the eleven months' stoppage the Trade Union recommended their acceptance. Ablett, with others like A. J. Cook (q.v.), formed an unofficial committee which issued a pamphlet called The Miners’ Next Step. This had been drafted by Ablett and is notable for its mixture of Syndicalism and Marxism. It contains a plea for the formation of one vast industrial union, and advocates workers’ control and ownership of industry. It had a large sale and provoked intense discussion in the industrial areas of the country. Ablett also wrote a number of articles for the Plebs magazine, the journal of the Labour College, and a book Easy Outlines of Economics. He was usually a lone dissenter on the Councils of the Union, which had adopted nationalisation of the mines as its policy rather than Ablett's Syndicalism.

He m. Ann Howells in 1912; they had two children. He d. 31 Oct. 1935 at Merthyr Tydfil.